[PATCH 0/6] dcache/namei fixes for lustre

From: NeilBrown
Date: Tue Aug 01 2017 - 23:07:36 EST


This series is a revised version of two patches I sent
previously (one of which was sadly broken).
That patch has been broken into multiple parts for easy
review. The other is included unchanged as the last of
this series.

I was drawn to look at this code due to the tests on
DCACHE_DISCONNECTED which are often wrong, and it turns out
they are used wrongly in lustre too. Fixing one led to some
clean-up. Fixing the other is straight forward.

A particular change here from the previous posting is
the first patch which tests for DCACHE_PAR_LOOKUP in ll_dcompare().
Without this patch, two threads can be looking up the same
name in a given directory in parallel. This parallelism lead
to my concerns about needing improved locking in ll_splice_alias().
Instead of improving the locking, I now avoid the need for it
by fixing ll_dcompare.

This code passes basic "smoke tests".

Note that the cast to "struct dentry *" in the first patch is because
we have a "const struct dentry *" but d_in_lookup() requires a
pointer to a non-const structure. I'll send a separate patch to
change d_in_lookup().

---

NeilBrown (6):
staging: lustre: llite: handle DCACHE_PAR_LOOKUP in ll_dcompare
staging: lustre: llite: use d_splice_alias for directories.
staging: lustre: llite: remove directory-specific code from ll_find_alias()
staging: lluste: llite: simplify ll_find_alias()
staging: lustre: llite: refine ll_find_alias based on d_exact_alias
staging: lustre: llite: fix incorrect DCACHE_DISCONNECTED test


drivers/staging/lustre/lustre/llite/dcache.c | 10 +++
.../staging/lustre/lustre/llite/llite_internal.h | 2 -
drivers/staging/lustre/lustre/llite/namei.c | 60 ++++++++++----------
3 files changed, 40 insertions(+), 32 deletions(-)

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